Yes, some of the Gibbon lines are polyester. Personally, I think they stuck, 1" slackspec webbing (polyester or nylon) is much better. Now, if you are talking about getting a tie down webbing system used for trucks and using that for slacklining - dont, it sucks.

yer i have looked at that stuff. to be honest the only real reason i was looking at the polyester line was because i found one with really cool print on it. so i was just weighing up quality vs cool looking.